A storage system is connected to at least one host computer and has a plurality of logical units therein. Further, the external storage system includes at least one or plural disk devices. The storage system and the host computer constitute a computer system. They are connected using an SCSI. Even in the case of a Fibre Channel or the like using no SCSI interface, a logical interface may be SCSI.
Such an external storage system in current use has coupling functions and is capable of copying logical units (LUs) between the present system and another external storage system. These coupling functions include a plurality of coupling operations. Commands for giving instructions for the respective operations are prepared. These coupling operations have been normally executed according to issuance of their corresponding commands from dedicated terminals. However, a method using command devices has also been considered as a method of directly executing coupling operations from a host computer. The host computer issues commands for performing the coupling operations to the command devices as data to be written into the external storage system. The command devices are shared logical units exclusively used for communication with the host computer. The host computer writes the commands into the dedicated command devices as data, whereas the external storage system processes the data written into the command devices as commands. Such coupling-operation instructions made from the host computer are executed by writing the commands into their corresponding command devices through an operation application (hereinafter abbreviated as RM) or an operation API (hereinafter abbreviated as RMLIB) on the host computer. The host computer is capable of giving instructions for the coupling operations from the command devices to all the logical units lying within the external storage system.
Meanwhile, if the instructions are written into the command devices, then they can be issued to all the logical units in the external storage system in the above related art. However, the following problems arise in reverse due to it.
While the external storage system can be connected to a plurality of host computers, accessible logical units are restricted for every host computer. It is thus necessary to limit instructions for coupling operations from a given host computer only to logical units accessible by the host computer. However, since the application on the conventional host computer is not provided with means for confirming whether a logical unit to be operated corresponds to the logical unit to be actually operated, which has been handled by the host computer, there is a possibility that the host computer will give instructions to a logical unit handled by another host computer, thus resulting in data corruption.
Connections of the logical units have heretofore been performed by confirming to which connection port the host computer is physically connected, confirming by means of a service processor, or the like, the configuration in which the host computer is connected, and manually developing the result thereof to a defined file on the host computer. Therefore, the possibility that data corruption will occur due to typing errors of a supervisor, still remains.
Therefore, a specific group, which makes use of a system (hereinafter called LUN security) implemented by Japanese Patent Application Laid-Open No. 2000-322369 at present, and which comprises a set of logical units in an external storage system, can be set so as to be recognized only by a specific Fibre Channel Port of a host computer. Further, the LUN security is extended even to command devices, and only command devices that belong to the same group, are applied so as to be able to operate their corresponding logical units.
Thus, when only one Fibre Channel Port is used in the host computer, the group of logical units recognized by the host computer is one, and all the logical units recognized by the host computer belong to one group. Therefore, the host computer is capable of operating all the logical units through the use of command devices that belong to the group.